Thermal reduction through activity based thermal targeting to enhance heating system efficiency

ABSTRACT

Thermal targeting technology is used to continuously adjust boiler target temperature to the minimum necessary to satisfy the required heating load. Responsive to and initiated by a first call for heat, boiler target temperature is reduced by a predetermined amount upon or subsequent to the call for heat. Once the boiler temperature reaches this new target, a call timer is activated. If demand for heat is satisfied before a time set point is reached, the system ceases providing additional heat energy until the next heat demand. Responsive to and initiated by a next call for heat, the boiler target temperature is again reduced by the predetermined amount upon or subsequent to this next call for heat. Each time the heat demand is satisfied within the predetermined time interval, the boiler target temperature is reduced. If heat demand is not satisfied, a thermal boost is provided at set time intervals until the call for heat is removed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for improvingthe efficiency of heating systems, specifically heating systems that usea boiler to heat an energy transfer medium, such as a fluid, forcirculation through heat exchangers in residential and commercialbuildings. More specifically, the present invention relates to anautomatic control of the boiler water target temperature for an improvedhot water heating system with the object of enhancing energy efficiencyduring operation in diverse and varying temperature environments throughthe systematic reduction of the boiler target temperature predicatedupon heating efficiency factors and external temperature conditions.

2. Description of Related Art

Hot water heating systems are closed-loop, fluid circulating systemsthat provide heat from an energy transfer medium, such as a fluid, andpump or circulate the energy transfer medium to an entire structure orzoned sections of a structure that requires a temperature increasegreater than the external ambient temperature.

A boiler heating system operates by way of heating an energy transfermedium to a preset temperature and circulating that fluid throughout abuilding or structure typically through heat exchangers, such asradiators, baseboard heaters, or the like, to warm the structure or atleast a portion of the structure. The fluid can be heated by any energysource, such as gas, or fuel oil, to name a few. The fluid is in anenclosed system and circulated throughout the structure within ingressand egress flow lines, such as conduits, usually by means of a motorizedpump or circulator.

When there is a call or demand for heat, such as a low thermostatreading in a zoned space within a structure that has realized a drop intemperature and requires more heat, or a low thermostat reading withinor near the boiler that registers a drop in transfer medium temperaturedue to a demand in usage, such as heating domestic hot water and havingthe temperature of the energy transfer medium decline as a result, aburner is fired within the boiler to heat the energy transfer mediumuntil the call for heat is removed or a predetermined boiler transfermedium temperature is reached, whichever comes first. The zoned spacesare responsive to changing ambient weather conditions in that thereoccurs continuously heat exchange between these zones and prevailingambient weather conditions. Once the demand for heat is satisfied, thedemand is removed, and the heating cycle repeats.

The efficiency of a boiler can be directly affected by the change intemperature of the outside environment. The ideal situation is toestablish a lower boiler water temperature in warmer weather when theboiler is in less demand, and higher boiler water temperature in colderweather, when the demand is high, dependent in part upon the thermalefficiency of the space being heated. A higher temperature heat deliverysystem will provide heat to a space more quickly, but is less efficientduring warmer ambient conditions insomuch as the burner fires for longerperiods of time or more often to keep the boiler water temperatureunnecessarily high.

With energy efficiency becoming of paramount importance, it is desirableto have a hot water heating system that can automatically adjust tochanging ambient conditions in a manner that allows the boiler tooperate more efficiently.

Furthermore, the widely accepted technology of an outdoor reset controlrequires the installation of a temperature sensor outside, typically toa Northern exposure location. Installation of this system islabor-intensive and time consuming. Moreover, building constraints willaffect structural placement of the outdoor reset control system.Additionally, without explicit building information, outdoor resetcontrols are typically conservatively set, resulting in a less efficientoperation.

Many prior art attempts have been made to control a heating system andmake the heating system more efficient by optimizing the heating cycle.In many circumstances, control circuitry and logic dictate the use oflower temperature boiler water for milder ambient weather than that usedor required under colder and more severe weather conditions. Thesesystems are uniquely different in that the methods for making a boilerresponsive to repetitive or prolonged calls or demands for heat employdifferent algorithms and logic, all differing in implementation andhaving various degrees of complexity.

For example, in U.S. Pat. No. 6,402,043, issued to Cockerill on Jun. 11,2002, entitled “METHOD FOR CONTROLLING HVAC UNITS,” the temperature setpoint of an HVAC unit is adjusted using two sensors. One sensor monitorsthe thermostat in a controlled environment, and a second sensor measuresthe temperature of the energy transfer medium. An ideal HVAC demandmodel is created for the controlled environment. The first sensor readsthermostat activity at set intervals over a defined period of time. Atthe conclusion of the defined time period, a microprocessor creates anactual demand model based on the recorded thermostat activity. Theactual HVAC demand model is then compared to the ideal HVAC demandmodel. A temperature change factor is calculated from the comparison. Anoptimum temperature set point for the HVAC unit is then determined. Themicroprocessor adjusts the actual temperature set point of the HVAC unitto the optimum temperature set point. The HVAC unit is then activatedwhenever the temperature of the energy transfer medium deviates from thetemperature set point by more than a predetermined set point range. Theefficiency of this system is dependent upon the accuracy of the idealdemand model created for a given structure.

In U.S. Pat. No. 6,409,090, issued to Gilvar, et al., on Jun. 25, 2002,entitled “SELF-OPTIMIZING DEVICE FOR CONTROLLING A HEATING SYSTEM,” theheating unit has an ON state initiated when a measurable variable of theheating medium, such as a temperature reading, reaches a maximum level.Once the heating unit is signaled ON, a timer measures the length oftime from initiation of the OFF state of the heating element until thetemperature of the heating medium decreases below a predeterminedminimum level. A processor then determines a delay time which delays theinitiation of the next ON state by the delay time amount. This isdistinctly different from systems that do not use a delayed initiation.

In contrast to reducing the temperature of the energy transfer medium,in U.S. Pat. No. 4,433,810, issued to Gottlieb on Feb. 28, 1984,entitled “HOT WATER HEATING SYSTEM,” operation of the heat exchangemedium's circulating pump is controlled. Control circuitry connects toboth the circulating pump and the boiler and works to lower the boileroperating temperature when detecting a significantly longer period ofnon-operation of the pump than a period of operation for a givenselected period of time. For a predetermined time interval, theoperation and non-operation of the pump is monitored. If the pump isnon-operational during this time period, this signifies that for theprevailing ambient weather conditions the temperature level of the hotwater being circulated through the heat system is unnecessarily high. Inthese instances, where the pump has only nominal operation, theoperating temperature level of the boiler is lowered because theexchange medium is running too hot. Importantly, it is the operation andnon-operation of the circulating pump that governs the temperaturecontrol. A consequence of the reduction in temperature of the heatexchange medium is that the circulating pump will remain ON for a longerperiod of time than prior to the temperature reduction. In this manner,a continuously running pump represents an optimum condition. Incomparison, the present invention reduces the boiler target temperatureon a demand for heat, and not simply for a period of time ofnon-operation of the circulator pump.

In U.S. Pat. No. 5,692,676, issued to Walker on Dec. 2, 1997, entitled“METHOD AND APPARATUS FOR SAVING ENERGY IN CIRCULATING HOT WATER HEATINGSYSTEMS,” a method is taught for automatically adjusting the temperatureof the boiler water in a hot water heating system in proportion tochanges in the heat demand rate in the space being heated, wherein thechange in heat demand rate is specifically established on the basis ofthe off-time interval in the cyclic OFF and ON activation of the pumpwhich circulates the water.

SUMMARY OF THE INVENTION

Bearing in mind the problems and deficiencies of the prior art, it istherefore an object of the present invention to provide a more efficientoperating method for a boiler heating system that seeks to acquire andutilize a lower boiler target temperature as a function of each call ordemand for heat.

It is another object of the present invention to incorporate a thermalboost to the heating system when a demand for heat cannot be timelyaccommodated, while simultaneously allowing for thermal reduction of theheating system when the demand for heat is reduced.

It is a further object of the present invention to decrease the boilertarget temperature when the demand for heat is reduced, and within apredetermined period of time between calls for heat.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The above and other objects, which will be apparent to those skilled inthe art, are achieved in the present invention which is directed to, ina first aspect, a method of improving efficiency of a boiler heatingsystem including adjusting boiler target temperature during heatingsystem operation, the method comprising: reducing the boiler targettemperature a predetermined amount to a reduced target temperature,ΔT_(reduce), such that the reducing is responsive to and initiated by acall for heat, and occurs upon or subsequent to the call for heat; andrunning the heating system at the reduced target temperature.

If the call for heat is satisfied while running heating system at thereduced target temperature, the method includes measuring time from apoint at which the call for heat is satisfied; and reducing the targettemperature a predetermined amount, ΔT_(reduce), each time apredetermined set time interval, t is reached without a subsequent callfor heat.

Moreover, if after a predetermined set time interval, t_(set), the callfor heat is unsatisfied at the reduced target temperature, the method ofthe present invention then increases the target temperature apredetermined amount, ΔT_(boost), and runs the heating system at theincreased target temperature.

If, however, the call for heat remains unsatisfied after the targettemperature has been raised the predetermined amount, ΔT_(boost), forthe predetermined set time interval, t_(set), measured from the increasein target temperature, the present invention increases the targettemperature a predetermined amount, ΔT_(boost), each time thepredetermined set time interval, t_(set), is reached without havingsatisfied the call for heat; and runs the heating system at theincreased target temperature.

Once the call for heat is satisfied, the method of the present inventionreduces the target temperature the predetermined temperature amount,ΔT_(reduce), such that the reduction is responsive to and initiated by asubsequent call for heat, and occurs upon or subsequent to thesubsequent call for heat.

The duty cycle of calls for heat may also be monitored such that if theduty cycle exceeds a predetermined value, the target temperature is nolonger reduced upon subsequent calls for heat. If the duty cycle exceedsa predetermined value, the predetermined set time interval, t_(set), iscontinued, disregarding interruptions in heat calls.

In a second aspect, the present invention is directed to a method ofimproving efficiency of a boiler heating system for heating a structure,the boiler heating system comprising: a burner; a controller incommunication with the burner for adjusting boiler target temperature; afirst temperature measurement device for measuring the boiler heatingsystem temperature, the first temperature measurement device incommunication with the controller; a second temperature measurementdevice for measuring temperature of the structure, the secondtemperature measurement device in communication with the controller; themethod comprising: adjusting the target temperature during heatingsystem operation, by reducing the target temperature a predeterminedamount to a reduced target temperature, ΔT_(reduce), such that thereducing is responsive to and initiated by a call for heat, and occursupon or subsequent to the call for heat, the call for heat triggered bythe second temperature measurement device communicating with thecontroller; running the heating system at the reduced target temperatureby having the controller communicate with and activate a circulator orthe burner; if the call for heat is satisfied while running the heatingsystem at the reduced target temperature: measuring elapsed time from atime at which a call for heat was satisfied; and reducing the targettemperature a predetermined amount, ΔT_(reduce), each time a firstpredetermined set time interval is reached without a subsequent call forheat; if the call for heat is unsatisfied while running the heatingsystem at the reduced target temperature: measuring elapsed time from atime when the target temperature was met; and increasing the targettemperature a predetermined amount, ΔT_(boost), after the elapsed timeequals to or exceeds a second predetermined set time interval; andrunning the heating system at the increased target temperature.

If the call for heat remains unsatisfied after the target temperaturehas been raised the predetermined amount, ΔT_(boost), at the secondpredetermined set time interval measured from the previous increase intarget temperature, in this aspect the present invention increases thetarget temperature the predetermined amount, ΔT_(boost), each time thesecond predetermined set time interval is reached without havingsatisfied the call for heat; and runs the heating system at theincreased target temperature.

Once the call for heat is satisfied, in this aspect the presentinvention reduces the target temperature the predetermined temperatureamount, ΔT_(reduce), such that the reduction is responsive to andinitiated by a subsequent call for heat, and occurs upon or subsequentto the subsequent call for heat.

In a third aspect, the present invention is directed to a method ofimproving the efficiency of a heating system comprising: setting apredetermined target temperature for an energy transfer medium within aboiler in the heating system; measuring a dynamic temperature of theenergy transfer medium within the boiler as a function of time;responsive to and initiated by a demand for heat for a zoned spacewithin a structure heated by the heating system: reducing the targettemperature a predetermined amount upon or subsequent to the demand forheat; circulating the energy transfer medium through the heating systemto at least one heat exchanger within the zoned space at the reducedtarget temperature; initiating a timer when the dynamic temperature ofthe energy transfer medium is approximately equal to the predeterminedtarget temperature; if the demand for heat is satisfied while runningthe heating system at the reduced target temperature: measuring elapsedtime from a point at which the call for heat is satisfied; and reducingthe target temperature the predetermined amount, each time a firstpredetermined set time interval is reached without a subsequent call forheat.

If the call for heat is unsatisfied while running the heating system atthe reduced target temperature, in this aspect the present inventionmeasures elapsed time from when the dynamic temperature of the energytransfer medium is approximately equal to the reduced targettemperature; sends a firing signal to a burner within the heating systemif the dynamic temperature of the energy transfer medium within theboiler is less than the predetermined target temperature within apredetermined differential temperature limit for the energy transfermedium; increases the target temperature a predetermined amount,ΔT_(boost), after the elapsed time equals to or exceeds a secondpredetermined set time interval; and runs the heating system at theincreased target temperature.

In a fourth aspect, the present invention is directed to a method ofimproving the efficiency of a heating system comprising: setting apredetermined temperature for a zoned space within a structure heated bythe heating system; setting a predetermined target temperature for anenergy transfer medium within a boiler in the heating system; measuringa dynamic temperature of the energy transfer medium within the boiler asa function of time; measuring a dynamic temperature of the zoned spaceas a function of time; triggering a call for heat upon a comparison ofthe temperature of the zoned space to the predetermined temperature forthe zoned space, such that if the comparison is greater than apredetermined temperature difference the call for heat is initiated;responsive to and initiated by the call for heat: reducing thepredetermined target temperature by a temperature reduction factor uponor subsequent to the call for heat; circulating the energy transfermedium through the heating system to at least one heat exchanger withinthe zoned space; and sending a firing signal to a burner within theheating system if the dynamic temperature of the energy transfer mediumwithin the boiler is, within a predetermined differential temperaturerange, less than the predetermined target temperature minus thetemperature reduction factor; initiating a timer when the dynamictemperature of the energy transfer medium is approximately equal to thepredetermined target temperature minus the temperature reduction factorfor the energy transfer medium; if the call for heat is satisfied withina first set time interval: reducing current target temperature by thetemperature reduction factor, and continuing to reduce the currenttarget temperature by the temperature reduction factor each time thefirst set time interval has elapsed without a subsequent call for heat.

In a fifth aspect, the present invention is directed to a method ofimproving efficiency of a boiler heating system including the steps of:providing a thermal reduction to the energy transfer medium within theboiler responsive to and initiated by a demand for heat to the heatingsystem, or when the demand for heat remains satisfied after apredetermined period of time, the thermal reduction comprising:decreasing a target temperature of the energy transfer medium within theboiler a first predetermined temperature interval upon or subsequent tothe demand for heat; and resetting the target temperature to the sum ofthe previous target temperature minus the first predeterminedtemperature interval; providing a system shut-off if the energy transfermedium exceeds a predetermined safety value; and combining the thermalreduction with low water cut-off protection for limiting the boilerheating system operation if the energy transfer medium volume is below apredetermined level, or with a boiler temperature limiting option, or acombination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel and the elementscharacteristic of the invention are set forth with particularity in theappended claims. The figures are for illustration purposes only and arenot drawn to scale. The invention itself, however, both as toorganization and method of operation, may best be understood byreference to the detailed description which follows taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a diagram of a heating system utilizing the thermal reductionalgorithm of the present invention for enhancing efficiency of a heatingsystem.

FIG. 2 depicts a timing diagram exemplifying the thermal reductionalgorithm of the present invention.

FIG. 3 is a timing diagram contrasting the average boiler temperatureand the outside temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In describing the preferred embodiment of the present invention,reference will be made herein to FIGS. 1-3 of the drawings in which likenumerals refer to like features of the invention.

A heating system is designed to provide a near constant room temperatureinside a dwelling regardless of outdoor temperature fluctuations. As theoutdoor temperature drops, the rate at which the dwelling loses heatincreases. Conversely, when the outdoor temperature increases, thedwelling is able to retain heat longer. For example, when thetemperature of a room within a structure falls below a predetermined setpoint, e.g., 66°, the thermostat switches ON and activates the heatingsystem to heat and circulate the energy transfer medium through conduitsto a heat exchanger within the room, such as a radiator. This generallycauses the temperature within the room to rise, although such factors asoutside air temperature, thermal insulation, and heat exchangerefficiency play important roles in the time-rate-of-change of thetemperature of the room. When the room temperature reaches apredetermined level, e.g., 68°, the thermostat switches OFF,deactivating the heating system. Heat then begins once again todissipate from the room at a rate dependent upon the thermal insulationand outside environment temperature.

As the outdoor temperature declines and the heat loss of the dwellingincreases, the heating system typically requires more time to satisfythe heat demand. As a result, thermostat calls increase in duration, andespecially so in situations where there is inadequate thermal insulationor diminished heat exchanger capacity or efficiency. As outdoortemperatures rise, the heating system is able to satisfy the heat demandmore quickly. Thus, in warmer environs, the thermostat calls are shorterin duration and spaced further apart. These scenarios and externalfactors make it difficult to adjust the temperature of the energytransfer medium within the boiler to an optimum level.

The present invention utilizes thermal targeting technology tocontinually adjust the boiler temperature to the minimum necessary toachieve the required heating load.

Referring to FIG. 1, a boiler 10 provides the heat energy to warm aspace 30, such as a room or zone in a residential or commercialbuilding. An energy transfer medium, such as a fluid, or the like, inboiler 10 is heated by burner 12, which is controlled by controlcircuitry or controller 14. The energy transfer medium receives the heatenergy from burner 12 and is pumped to heat exchanger 16 by circulator25 through outflow line or conduit 20. Outflow line 20 connects to, andis in fluid communication with, a heat exchanger 16, such as a radiator,and the like, in space 30. As the energy transfer medium flows throughheat exchanger 16, heat from the energy transfer medium is converted byheat exchanger 16, and ultimately warms space 30. In a forced, hot waterheating system, the energy transfer medium is water. Upon return fromheat exchanger 16, the energy transfer medium flows to inflow line orconduit 22, and returns back to boiler 10. Sensors, for exampletemperature sensors in hot water systems, are used to monitor thetemperature of the energy transfer medium in flow lines 20, 22, orwithin boiler 10, or any combination thereof. Domestic hot water mayalso be supplied by boiler 10. Heat exchanger 28 is located withinboiler 10, which receives water from an external supply and heats thewater by transferring heat energy from the boiler. Domestic hot waterthen traverses through conduit 26 which delivers the hot water to thedemand site.

In the present invention, controller 14 establishes a boiler targettemperature, T_(target), for the energy transfer medium within boiler10, and upon a call or demand for heat, circulator 25 is activated, andburner 12 is fired until the target temperature is reached. The targettemperature is derived from the previous heating cycle targettemperature. The present invention reduces the previous heating cycletarget temperature in a manner that is responsive to and initiated by acall for heat, and upon or subsequent to the call for heat, establishinga lower target temperature, T_(target). Although this thermal reductionof the boiler target temperature appears contrary to the application ofthe heating system upon a demand for heat, it provides the salientefficiency enhancement of the present invention.

The controller 14 maintains the energy transfer medium temperaturewithin a differential range, ΔT_(diff), about the newly set targettemperature, such that the boiler temperature remains in the range ofT_(target)±ΔT_(diff). Preferably, there will be a sliding scale for adifferential off the target temperature, although constant differentialtemperature values may certainly be accommodated. The differentialtemperatures based on a sliding scale are preferably dependent upon theabsolute value of the target temperature in order to avoid a situationwhere the boiler target temperature is held at too low of a temperature.In this manner, as the target temperature is initially reduced with eachcall, each lower target temperature value will be associated with asmaller amount of differential or deviation. Thus, ΔT_(diff) will belower in absolute value when associated with lower boiler targettemperatures, and higher in absolute value when associated with higherboiler target temperatures.

Responsive to and initiated by a demand for heat, controller 14 isprogrammed to set the boiler target temperature lower, upon orsubsequent to the demand for heat, which provides a thermal reduction tothe previous target temperature of the energy transfer medium withinboiler 10 by a temperature, ΔT. Thus, the new boiler target temperaturebecomes the previous boiler target temperature minus the thermalreduction temperature: T_(target(new))=T_(target(old))−ΔT_(reduce).Based on this new temperature value, the differential or variance isthen applied to give the boiler target temperature an operating range:T_(target(new))±ΔT_(diff). A call timer is initiated once the energytransfer medium reaches the newly reduced target temperature. If thedemand for heat is satisfied within a predetermined set time interval,t_(set), responsive to and initiated by the next call for heat, theprevious target temperature is again reduced, upon or subsequent to thecall for heat, while the system attempts to meet the new heat demandwithin the time interval t_(set). If the demand for heat is notsatisfied when the call timer reaches the predetermined set timeinterval, t_(set), the boiler target temperature is increased intemperature a predetermined amount, which is referred to as a thermalboost, ΔT_(boost). Preferably, the thermal boost is in a constanttemperature interval, although it may be in any predetermined intervalpredicated upon other system characteristics and environmentalconditions, and could be represented by a function rather than aconstant. In this manner, the new target temperature becomesT_(target)+ΔT_(boost), where T_(target) represents the previouslyreduced target temperature value based on the initial thermal reductionalgorithm.

In a preferred embodiment, the logic control circuitry would evaluateand adjust the target temperature (T_(target)) of the energy transfermedium at a set time interval, for example, at t_(set)=20 minutes,although as previously discussed, other set time intervals may bepreferred, and can be accommodated for different heating systemconfigurations and structure considerations. Predetermined temperatureselections may also be based on overlapping calls for heat in amulti-zoned structure. It is envisioned that an operator may adjust orpreselect the set time using preselected time intervals such that, forexample, t_(set) may be selected by the operator from a range of valueswhere t_(set)=10, 15, 20, 25, 30, 35, 40, or 45 minutes, or t_(set) maybe represented analytically as a function of time or temperature.

If, upon thermal reduction of the target temperature pursuant the methodof the present invention, the demand for heat is satisfied within theset time period, t_(set), then there is an immediate energy savingsinsomuch as the boiler target temperature is repeatedly lowered witheach call for heat satisfied within the set time period, t_(set), but ineach case is still able to accommodate the demand for heat. If, however,the demand for heat is not satisfied within a given time period,t_(set), the temperature of the energy transfer medium in the boiler, T,is considered to be insufficiently low. Burner 12 is ordered to fire,and the energy transfer medium within boiler 10 is heated to a highertarget temperature, increased by the thermal boost:T=T_(target)+ΔT_(boost). In one embodiment, ΔT_(boost) is set at apredetermined amount, such as ten degrees (10° F.), above the initialenergy transfer medium temperature setting, T_(target), although thispredetermined amount may be represented by other constant values, orother functional relationships, and the invention is not limited to asingle value. This cycle is repeated until the heat demand is satisfied.

Heat efficiency gains are significantly realized when the heating systemis subjected to different outside environments. When the outsideenvironment warms, the heating system does not have to work as hard toprovide heat energy to the structure, since heat dissipation from thestructure is considerably reduced. The boiler target temperature couldconceivably be running too hot for delivering the amount of heat energynecessary to maintain consistent heat in a slowly dissipating structure.In this scenario, the thermal reduction feature of the present inventiongoverns the enhanced efficiency algorithm.

The boiler target temperature will be initially reduced responsive toand initiated by a call for heat, and upon or subsequent to the call forheat, by a predetermined amount, such thatT_(target)=T_(initial)−ΔT_(reduce). If the demand for heat is satisfiedbefore the t_(set) point is reached, the system ceases providingadditional heat energy until the next heat demand. Responsive to andinitiated by the next call for heat, and upon or subsequent to this nextcall for heat, the boiler target temperature is again reduced by thepredetermined amount, ΔT_(reduce), and the new target temperature isagain represented asT_(target)=(T_(initial)−ΔT_(reduce))−ΔT_(reduce)=T_(initial)−2ΔT_(reduce).Each time the heat demand is satisfied, the boiler target temperature isreduced responsive to and initiated by the next call for heat, and uponor subsequent to the next call for heat. Under this scenario the thermalreduction algorithm may be generally represented in the followingmanner:T _(target)=(T _(initial) −N _(r) *ΔT _(reduce))

-   -   where,    -   T_(initial)=initial or previous boiler target temperature    -   ΔT_(reduce)=temperature reduction factor; and    -   N_(r)=number of thermal reductions;

Once the energy transfer medium reaches the target level, a call timeris activated and t_(set) is monitored. If the demand for heat is notsatisfied within time period t_(set), a thermal boost is performed. Ananalytical representation of the thermal boost scenario is determined inthe following manner. Once it is understood that the heat demand is notsatisfied after the predetermined time interval, t_(set), a firstthermal boost is administered. Upon thermal boost, the call timer isreset. Subsequent thermal boosts are then administered at each timeinterval t_(set) until the heat demand is met or a system temperaturelimit is achieved. Under this scenario, this portion of the systemalgorithm representing boiler target temperature may be expressed asfollows:T _(target)=[(T _(initial) −ΔT _(reduce))+(N _(b) *ΔT _(boost))]

-   -   where,    -   T_(initial)=initial or previous boiler target temperature;    -   ΔT_(reduce)=temperature reduction factor;    -   ΔT_(boost)=temperature boost factor; and    -   N_(b)=number of thermal boosts

Thus, in situations where the heat demand cannot be satisfied within aset time interval, the boiler target temperature which was initiallyreduced by a temperature ΔT_(reduce), is then raised by a temperatureΔT_(boost). For each subsequent time interval, t_(set), for which thedemand for heat remains unsatisfied, a subsequent thermal boost isperformed. The temperature increase is preferably the same increaseestablished for the first thermal boost interval, although anytemperature increase algorithm may be adopted, and the present inventionis not limited to a single or constant temperature increase. Forexample, the subsequent temperature increases may follow a decreasingexponential function in relation to the thermal dissipation realized bythe space being heating.

As an illustrative example in a warm environ, where the outsidetemperature is rapidly rising, and assuming an initial boiler targettemperature of 165° F., a thermal reduction temperature of 5° F., and athermal boost temperature of 10° F., a first call for heat would reducethe boiler target temperature such that T_(target)=165° F.−5° F.=160° F.[T_(target)=T_(initial)−ΔT_(reduce)]. After a set time, t_(set), due tothe warm outside environment or slow heat dissipation from thestructure, the demand for heat is presumably satisfied. Responsive toand initiated by the next call for heat, and upon or subsequent to thisnext call for heat, a new target temperature is set based upon anotherthermal reduction: T_(target)=160° F.−5° F.=155° F.[T_(target)=T_(initial)2*ΔT_(reduce)]. Continuing with this logic, ifprior to another set time period, t_(set), the demand for heat is againsatisfied, the new boiler target temperature responsive to or initiatedby the next call for heat will be adjusted for another reduction upon orsubsequent to this next call for heat: 155° F.−5° F.=150° F.[T_(target)=3*ΔT_(reduce)]. In each instance, the target temperaturesare set and the new boiler target temperature operating range isT_(target)±ΔT_(diff).

As an illustrative example of the second scenario, in a cold environwhere the outside temperature is rapidly falling, assuming an initialboiler target temperature of 165° F., a thermal reduction temperature of5° F., and a thermal boost temperature of 10° F., a first call for heatwould reduce the boiler target temperature such that T_(target)=165°F.−5° F.=160° F. [=T_(initial)−ΔT_(reduce)]. Assuming that after a settime, t_(set), due to the cold outside environment, the demand for heatis still not satisfied, a new target temperature is set based on athermal boost: T_(target)=160° F.+10° F.=170° F.[=T_(target(previous))+ΔT_(boost)]. Continuing with this logic, afteranother set time period, t_(set), assuming the demand for heat is stillnot met, the new boiler target temperature is adjusted by anotherthermal boost: T_(target)=170° F.+10° F.=180° F.[=(T_(initial)−ΔT_(reduce)) N_(b)*ΔT_(boost)]. In each instance, thetarget temperatures are set and the new boiler target temperatureoperating range is T_(target)±ΔT_(diff).

This cycle is repeated if the demand for heat remains unsatisfied oruntil the energy transfer medium's temperature reaches a predeterminedsystem maximum, which is typically based upon operational safetyconsiderations.

An additional efficiency measure, which may be used in conjunction withthe above stated thermal reduction algorithm, is to decrease the boilertarget temperature whenever a second predetermined time intervalt_(set2) has been realized without any call or demand for heat. Forinstance, if there has not been a call for heat within thirty minutes(t_(set2)=30 minutes), the control circuitry would decrease the targettemperature of the energy transfer medium within the boiler by apredetermined value ΔT_(reduce2).

FIG. 2 depicts a timing diagram exemplifying the thermal efficiencyalgorithm of the present invention in instances where the outsidetemperature is first rising and then falling. The x-axis represents timeand the y-axis represents temperature. The variable thermostattemperature reading in the space being heated is depicted by line 44.Thermostat ON-OFF calls are depicted by line 46. Prior to a call forheat, thermostat reading in section 50 a is shown having a drop intemperature, indicating that the space being monitored has cooled off.In this time period, the outside temperature, represented by line 48 isshown rising, i.e., the temperature outside the structure is increasing.If the thermostat reading drops a certain amount below a predeterminedset point, for example two degrees (2° F.) below the set roomtemperature, there will be a call for heat, identified as time t_(call).The thermostat call will be activated (ON) as shown in section 50 b.

At this time, t_(call), the heat efficiency algorithm of the presentinvention is initiated. Responsive to and initiated by a call for heat,the boiler target temperature is reduced by a predetermined amount,ΔT_(reduce), upon or subsequent to this call for heat. In thisillustrative example, the thermal reduction is responsive to andinitiated by the call for heat, and applied immediately upon the callfor heat; but the present invention is not limited to the particulartime when the thermal reduction is made, and in fact, the thermalreduction may be performed any time from immediately at the onset of thecall for heat to a time subsequent thereto. The burner and circulatorare turned on, and the temperature within the boiler is brought up tothis reduced target temperature within a predefined differential value.Once the boiler is at target temperature the burner is turned off and anew time clock starts measuring time interval t_(set) during thermostatactivation, and the system continues to run until the heat demand issatisfied or t_(set) reaches a predetermined value. In this firstinstance, the system is shown satisfying the heat demand before t_(set)reaches its predetermined limit, and the thermostat call is turned OFFat time t₁.

At a later time t₂, the system still does not require another call forheat. If the time between t₂ and t₁ is greater than or equal to apredetermined set interval t_(set2) for thermostat deactivation, whichmonitors the time between calls for heat, the boiler target temperatureis again reduced at time t₂. Since the outside environment continues towarm during this time period, it is anticipated that there will be fewercalls for heat, and the reduction in boiler target temperature providesan efficiency enhancement. Following the logic shown by the chart, asecond time interval of t is reached at time t₃, such thatt₃−t₂=t_(set2), where the boiler target temperature is again reduced.Again, the thermal reduction algorithm of the present invention islowering the boiler target temperature at each opportunity in order toenhance the heating system efficiency.

At time t₄, which is the start of section 50 c, the outside environmentis shown cooling off with decreasing temperature, and there is a secondcall for heat; thermostat activation 46 is ON. Under the current thermalreduction algorithm, the first action would be to lower the boilertarget temperature by an amount ΔT_(reduce); however, at thistemperature point in the system operation a predetermined target minimumlimit has been met. Consequently, the boiler target temperature remainsat this low point and the heating system attempts to satisfy the callfor heat. As shown at time t₅, the heat demand remains unsatisfied. Inthis example, the difference between t₅ and t₄ is the predetermined setinterval t_(set), such that t₅−t₄=t_(set), which means the heatingsystem has been unable to adequately heat the structure during the timeinterval t_(set) at this boiler target temperature limit. Thus, athermal boost is employed at time t₅. The thermal boost raises theboiler target temperature, and a new time clock is reset while theheating system continues to provide heat. A short time later, t₆, thedemand for heat is shown to have been satisfied. The boiler targettemperature remains at the boosted temperature and a new time clockstarts for measuring the next t_(set2) interval.

At this stage, the outside environment and the room temperature areshown in section 50 d as cooling off. Once again a time intervalt_(set2) is shown being met at time t₇, such that t₇−t₆=t_(set2),without having a call for heat. The thermal reduction algorithm isemployed at t₇ and the boiler target temperature is decreased by anamount ΔT_(reduce). As shown, the outside environment decreases intemperature, the room temperature decreases as well, and by time t₈, thethird thermostat call is activated. The system employs the thermalreduction algorithm and reduces the boiler target temperature by anamount ΔT_(reduce). The heating system runs at this temperature untilt₉, where t₉−t₈=t_(set), and the call for heat remains active. At thispoint, a thermal boost is initiated and the heating system runs at thisincreased boiler temperature.

FIG. 3 is a timing diagram contrasting the average boiler temperature 40with the outside temperature 48 when the heating system is operatedpursuant to the present invention. As depicted in FIG. 3, the averageboiler temperature will inversely follow the outside temperature.

This cycle repeats with obvious increases in the amount of thermalreductions to the boiler target temperature during times of warmeroutside temperatures, and increases in the amount of thermal boosts tothe boiler target temperature during times of cooler outsidetemperatures.

An additional measure is implemented within the thermal boost scheme ofthe present invention, which is the added monitoring of the system'sduty cycle. If the duty cycle of the thermostat exceeds a given value,such as ninety percent (90%), the thermostat interruptions will betreated as a continuous call by the present invention's thermaltargeting functions. The duty cycle is preferably monitored in a rollingmeasurement, for example, over a one hour period in one minute timeintervals. Added duty cycle monitoring allows the heating system tocheck itself under dynamic conditions where temperature reductions wouldnot be desirable or would result in the system's inability to provideadequate heat. For example, if the duty cycle is ninety percent (90%),there is probably no need to bring down the temperature as the systemnormally would do in a less aggressive duty cycle mode. Thermal boostingcontinues until the duty cycle decreases, or the system's operationaltemperature limit is reached.

The present invention may be utilized in tandem with other protectivefeatures and options associated with boiler operation. For example, lowwater cut-off and boiler temperature limiting options may be employedconcurrently with the present invention, and may be operated orcontrolled by controller 14.

Salient features of the present invention include the systematicoperation of decreasing incrementally the temperature of the boilertarget temperature and the energy transfer medium within the boiler inorder to save energy during operation. Preferred variable thermalreductions at predetermined time intervals, and thermal boosts, or acombination thereof are employed to achieve greater thermal efficiencyof the heating system.

While the present invention has been particularly described, inconjunction with a specific preferred embodiment, it is evident thatmany alternatives, modifications and variations will be apparent tothose skilled in the art in light of the foregoing description.

It is therefore contemplated that the appended claims will embrace anysuch alternatives, modifications and variations as falling within thetrue scope and spirit of the present invention.

Thus, having described the invention, what is claimed is:
 1. A method ofimproving efficiency of a boiler heating system including adjustingboiler target temperature during heating system operation, said methodcomprising: reducing said boiler target temperature a predeterminedamount to a reduced target temperature, ΔT_(reduce), such that saidreducing is responsive to and initiated by a call for heat, and occursupon or subsequent to said call for heat; running said heating system atsaid reduced target temperature; and monitoring a duty cycle of callsfor heat such that if said duty cycle exceeds a predetermined value,said target temperature is no longer reduced upon subsequent calls forheat.
 2. The method of claim 1 including, if after a predetermined settime interval, t_(set), said call for heat is unsatisfied at saidreduced target temperature, increasing said target temperature apredetermined amount, ΔT_(boost), and running said heating system atsaid increased target temperature.
 3. The method of claim 2 including,if said call for heat remains unsatisfied after said target temperaturehas been raised said predetermined amount, ΔT_(boost), for saidpredetermined set time interval, t_(set), measured from said increase intarget temperature: increasing said target temperature a predeterminedamount, ΔT_(boost), each time said predetermined set time interval,t_(set), is reached without having satisfied said call for heat; andrunning said heating system at the increased target temperature.
 4. Themethod of claim 3 including, once said call for heat is satisfied,reducing said target temperature said predetermined temperature amount,ΔT_(reduce), such that said reducing is responsive to and initiated by asubsequent call for heat, and occurs upon or subsequent to saidsubsequent call for heat.
 5. The method of claim 2 wherein saidpredetermined set time interval, t_(set), is calculated based on aconstant value, a sliding scale, or a predetermined function.
 6. Themethod of claim 2 wherein temperature increase value ΔT_(boost) iscalculated based on a constant value, a sliding scale, or apredetermined function.
 7. The method of claim 2 including monitoring aduty cycle of calls for heat such that if the duty cycle exceeds apredetermined value, said predetermined set time interval, t_(set), iscontinued, disregarding interruptions in heat calls.
 8. A method ofimproving efficiency of a boiler heating system for heating a structure,said boiler heating system comprising: a burner; a controller incommunication with said burner for adjusting boiler target temperature;a first temperature measurement device for measuring said boiler heatingsystem temperature, said first temperature measurement device incommunication with said controller; a second temperature measurementdevice for measuring temperature of said structure, said secondtemperature measurement device in communication with said controller;said method comprising: adjusting said target temperature during heatingsystem operation, by reducing said target temperature a predeterminedamount to a reduced target temperature, ΔT_(reduce), such that saidreducing is responsive to and initiated by a call for heat, and occursupon or subsequent to said call for heat, said call for heat triggeredby said second temperature measurement device communicating with saidcontroller; running said heating system at said reduced targettemperature by having said controller communicate with and activate acirculator or said burner; if said call for heat is satisfied whilerunning said heating system at said reduced target temperature:measuring elapsed time from a time at which a call for heat wassatisfied; and reducing said target temperature a predetermined amount,ΔT_(reduce), each time a first predetermined set time interval isreached without a subsequent call for heat; if said call for heat isunsatisfied while running said heating system at said reduced targettemperature: measuring elapsed time from a time when said targettemperature was met; and increasing said target temperature apredetermined amount, ΔT_(boost), after said elapsed time equals to orexceeds a second predetermined set time interval; and running saidheating system at said increased target temperature; if said call forheat remains unsatisfied after said target temperature has been raisedsaid predetermined amount, ΔT_(boost), at said second predetermined settime interval measured from said previous increase in targettemperature: increasing said target temperature said predeterminedamount, ΔT_(boost), each time said second predetermined set timeinterval is reached without having satisfied said call for heat; andrunning said heating system at the increased target temperature; andmonitoring a duty cycle of said call for heat such that if said dutycycle exceeds a predetermined value, said target temperature is nolonger decreased upon subsequent demands for heat.
 9. The method ofclaim 8 including monitoring said duty cycle in a rolling measurement.10. The method of claim 9 wherein said monitoring includes measuringsaid duty cycle over a period of one (1) hour in multiple time segments.11. A method of improving efficiency of a boiler heating system forheating a structure, said boiler heating system comprising: a burner; acontroller in communication with said burner for adjusting boiler targettemperature; a first temperature measurement device for measuring saidboiler heating system temperature, said first temperature measurementdevice in communication with said controller; a second temperaturemeasurement device for measuring temperature of said structure, saidsecond temperature measurement device in communication with saidcontroller; said method comprising: adjusting said target temperatureduring heating system operation, by reducing said target temperature apredetermined amount to a reduced target temperature, ΔT_(reduce), suchthat said reducing is responsive to and initiated by a call for heat,and occurs upon or subsequent to said call for heat, said call for heattriggered by said second temperature measurement device communicatingwith said controller; running said heating system at said reduced targettemperature by having said controller communicate with and activate acirculator or said burner; if said call for heat is satisfied whilerunning said heating system at said reduced target temperature:measuring elapsed time from a time at which a call for heat wassatisfied; and reducing said target temperature a predetermined amount,ΔT_(reduce), each time a first predetermined set time interval isreached without a subsequent call for heat; if said call for heat isunsatisfied while running said heating system at said reduced targettemperature: measuring elapsed time from a time when said targettemperature was met; and increasing said target temperature apredetermined amount, ΔT_(boost), after said elapsed time equals to orexceeds a second predetermined set time interval; and running saidheating system at said increased target temperature; if said call forheat remains unsatisfied after said target temperature has been raisedsaid predetermined amount, ΔT_(boost), at said second predetermined settime interval measured from said previous increase in targettemperature: increasing said target temperature said predeterminedamount, ΔT_(boost), each time said second predetermined set timeinterval is reached without having satisfied said call for heat; andrunning said heating system at the increased target temperature; andmonitoring a duty cycle of calls for heat such that if the duty cycleexceeds a predetermined value, said second predetermined set timeinterval is continued, disregarding interruptions in heat calls.